贺兰山小松山基性－超基性杂岩体岩石地球化学特征  

Lithogeochemical Characteristics of Basic-Ultrabasic Intrusion,Xiaosongshan,Helanshan

作　　者：黄喜峰[1] 钱壮志[1] 吴文奎[1] 孙保平[1] 逯东霞[1] 王成 陆彦俊 

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]宁夏地质调查研究院,宁夏银川750021

出　　处：《地球科学与环境学报》2008年第4期351-356,共6页Journal of Earth Sciences and Environment

基　　金：国家重点基础研究发展计划项目(2003CB214600);中国地质调查局项目(J48C001003;J48C002003)

摘　　要：贺兰山小松山岩体的岩石地球化学研究表明，基性岩的Mg^#为0．71～0．76，接近原生岩浆的值，超基性岩的Mg^#为0．80～0．89，具有岩浆早期堆晶的特征，稀土总量∑REE为（13．03～82．66）×10^-6；δ（Eu）为1．08～1．61，具弱正异常；（La／Yb）N为2．49～5．24，（Ce／Yb）N为3．01～4．97，配分曲线表现为轻稀土相对富集的右倾型。微量元素配分曲线图表现为大离子亲石元素富集。岩石地球化学数据综合分析证明，该岩体产于板内拉张环境，岩体形成过程中经历了岩浆分离结晶作用，后期发生了同化混染，岩体具有寻找铬-铜-镍型岩浆矿床的潜力。The Xiaosongshan basic-ultrabasic complex is consists of three closely associated rocks （peridotite, gabbro and pyroxenite）. The Mg^# of the basic rocks is 0.71 to 0.76, which is similar to Mg^# of the original magma. The Mg^# of the ultrabasic rocks is 0.80- 0. 89, demostrates the characteristics of early cumulation of magma. The total ∑REE is 13.03× 10^-6 to 82.66× 10^-6 , the δ（Eu） is 1.08 to 1.61 which shows a weak positive Eu anomaly, the （La/Yb） N is 2.49 to 5, 24, and the （Ce/Yb） N is 3.01 to 4.97. The normalized REE patterns of the Xiaosongshan complex are relatively enriched in LREE and belong to the right-inclined type. The trace element patterns show enrichment in LILE. These lithogeochemical data suggest that the Xiaosongshan complex was formed in intra-plate extension environment. The forming processes of the Xiaosongshan complex may include fractional crystallization in the early and contamination in the late. Therefore, the Xiaosongshan complex has potential advantages in searching magmatic deposit of Cr-Cu-Ni type.

关 键 词：岩石地球化学 大地构造环境 分离结晶 同化混染 小松山基性-超基性岩体 

分 类 号：P588.12[天文地球—岩石学]